Withdrawn: 8340814: ZipFileInflaterInputStream should release its Inflater after observing EOF

[duke]

On Tue, 24 Sep 2024 13:31:25 GMT, Eirik Bjørsnøs <eirbjo at openjdk.org> wrote:

> Please consider this PR which makes `ZipFileInflaterInputStream` release its `Inflater` instance back to the pool when observing that the stream has been fully consumed.
> 
> This is motivated by the following observations:
> 
> * After a `ZipFileInflaterInputStream` has reached the end of stream, its `Inflater` instance no longer does useful work.
> * Obtaining an input stream via `ZipFile::getInputStream` without properly closing it is probably common. Obtaining it without fully consuming it is probably more rare. (Something like `classLoader.getInputStream(entry).readAllBytes()` is probably common)
> * While GC will eventually release the `Inflater` when the `Cleaner` closes the stream, this will only happen at some later point in time. In the meantime, `ZipFile::getInputStream` may produce many new `Inflater` instances. These will all be released to the pool once GC eventually catches up.
> * Once an `Inflater` is released to to pool, it will stay there for the lifetime of the `ZipFile`
> * The lifetime of a `ZipFile` may often be as long as the application (consider class loaders).
> 
> This PR suggests the following changes:
> 
> * Rename the existing field `ZipFileInflaterInputStream.eof` to `compressedEof`. (This tracks the EOF of the filtered input stream)
> * Add a new field  `ZipFileInflaterInputStream.eof` to track the EOF of uncompressed data.
> * Override  `ZipFileInflaterInputStream.read(byte[] b, int off, int len)` to detect the EOF of uncompressed data and release the `Inflater` instance back to the pool when it is no longer needed.
> * To protect the `Inflater` instance from being used after being released and reset, the following updates are needed:
>   * `ZipFileInflaterInputStream.read` must check if EOF has been reached  but that the stream has not yet been closed. In this case, EOF should be returned.
>   * Similarly, `ZipFileInflaterInputStream.available` needs an update to return 0 if EOF has been detected.
> 
> The PR adds a test `ReleaseInflaterOnEOF` which verifies that all fully consumed input streams are backed by the same `Inflater` instance.
> 
> This PR was inspired by JDK-7031076 and this discussion: https://mail.openjdk.org/pipermail/core-libs-dev/2011-March/006341.html

This pull request has been closed without being integrated.

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PR: https://git.openjdk.org/jdk/pull/21157